In semiconductor pattern dimension measurement, a high-resolution image sensed by a scanning electron microscope (SEM) is used to obtain coordinates of pattern edges on an image; then, dimensions are calculated from edge coordinates of both ends thereof. If the pattern is a straight line and simultaneously is in parallel with the vertical direction or horizontal direction of a display image, it is possible to readily obtain the pattern dimensions from a difference of coordinate values in the horizontal or vertical direction of both edges. However, there is an exemplary case where special shape patterns having curved line portions are employed for the purpose of achieving higher density of semiconductor circuits. In these patterns, a direction indicating the shortest distance between edges to be regarded as a size value tends to vary continuously; so, mere use of the above-noted prior known method does not enable achievement of accurate dimension measurement. In addition, even where the pattern is a straight line, when the pattern is a pattern extending in a direction inclined with respect to the display image, it is similarly difficult to perform accurate dimension measurement.
It is noted here that Patent Literature 1 discloses therein a technique for performing measurement of a pattern inclined with respect to a display image; more specifically, a scheme for acquiring, based on a figure reflecting the shape of a very small or fine pattern, a signal waveform in a direction perpendicular to a tangent line of the contour of a graphic form and for detecting pattern edge coordinates to thereby measure the pattern shape.